Methods and systems for improving combustion processes

ABSTRACT

Methods, systems, and kits directed to improving combustion processes. In one embodiment, a method includes applying air to an internal surface of a combustion system. The air may be applied with a velocity chosen from about 50 m/s to about 300 m/s, and a volumetric flow chosen from about 50 ACFM to about 4000 ACFM. At least one FCT chemical may be optionally fed with the injected air in this embodiment.

FIELD OF TECHNOLOGY

The present inventions relate generally to methods and systems forimproving combustion processes, and more particularly to methods andsystems for reducing the occurrence of at least one combustion problemchosen from ash accumulation, corrosion and incomplete combustion.

BACKGROUND

Combustion systems are known in the art and can include, for example,pulverized coal plants, circulated fluidized beds, gas-fired systems,oil-fired systems, waste incinerators, direct-fired process heaters,tangentially-fired boilers, wood burning systems, etc. Common elementsof various combustion systems typically include a combustion chamber anda burner for igniting fuel located in the combustion chamber. FIG. 1shows one example of a combustion system 1 including boiler 2 andcombustion chamber 4. Fuel (e.g. coal) is fed through feed 5 tocombustion chamber 4, where it is rapidly ignited by burners 5 a tocreate flame 5 b. The resulting flame sends heat and/or flue gas intovarious areas of the system, e.g. 6 a, 6 b, 6 c, 6 d, 6 e, etc.Combustion system parts can include walls 7 a, boiler drum 7 b,superheater 7 c, reheater 7 d, economizer 7 e, and air heater 7 f.

To briefly summarize operation of the depicted combustion system, butwithout limitation, boiler drum 7 b is where steam produced bycombustion is separated from water. Steam then travels to superheater 7c where its temperature increases rapidly. From superheater 7 c, steamis piped to a turbine (not shown). Steam from the turbine is returned toreheater 7 d, where it is reheated. From reheater 7 d, steam is piped toanother turbine stage (not shown). Steam from this turbine stage is thencondensed before being reheated in economizer 7 e. From economizer 7 e,steam can be fed to drum 7 b to repeat the cycle. Those of ordinaryskill in the art will recognize that the above description of parts andfunction is illustrative, and that combustion systems may come in avariety of different configurations. Regardless of the combustionsystem's construction, efficient operation is desirable.

Combustion, however, can create several problems that contribute toreduced efficiency or increased operating costs in systems havingboilers as well as other types of combustion systems. For example,combustion may produce the accumulation of material, such as ash 8 oninternal surfaces, e.g., walls 7 a, boiler drum 7 b, superheater 7 c,reheater 7 d, and economizer 7 e, or other upstream or downstream parts.Ash accumulation is undesirable because it results in, inter alia, aloss of heat transfer, slag formation, fouling, pressure drop acrossheat transfer surfaces, clinkers, plugging, etc. Further, corrosion 10may occur as a result of ash accumulation, potentially requiringexpensive repairs to system parts, e.g., tube surfaces of a boiler. As aresult, some try to remove ash accumulation by physical means, e.g.,soot blowing, detonation, or shotgunning. Some also try to remove ashaccumulation by chemical injection or by sonic disruption.

Another problem sometimes present in combustion systems is theoccurrence of incomplete combustion, which can result in significantamounts of unburned fuel and lost energy.

The various embodiments of the invention provide various advancements inthe art.

SUMMARY

By way of summary, the disclosure is directed to, inter alia, reducingthe occurrence of at least one problem chosen from ash accumulation andcorrosion. The disclosure is also directed to, inter alia, catalyzingcombustion, e.g., reducing the amount of unburned fuel in a combustionsystem.

In some embodiments, the invention includes methods for reducing theoccurrence of at least one of ash accumulation and corrosion. Oneembodiment includes providing a combustion system capable of emitting aflue gas and applying air to an internal surface of the combustionsystem (an ISCS) to reduce the occurrence of at least one of ashaccumulation and corrosion. In one embodiment, the application of air tothe ISCS occurs by transferring air from one or more entry points of thecombustion system to the ISCS using at least one apparatus. Air is oftenapplied with a velocity chosen from about 50 to about 300 m/s, and avolumetric flow chosen from about 50 to about 4000 actual cubic feet perminute (ACFM). In one embodiment, air application is sufficient toincrease the oxygen concentration in flue gas contacting an ISCS portionof concern to about 2% or greater. In another embodiment, airapplication is sufficient to decrease the CO concentration in flue gascontacting the ISCS to less than 5000 ppm CO. In another embodiment, atleast one fireside chemical treatment (FCT) chemical is applied into thecombustion system to further reduce the occurrence of at least one ofthe above mentioned problems. In another embodiment, at least one FCTchemical is fed into the applied air such that the at least one FCTchemical and air are applied together, for example, via one or moreapparatuses configured to apply air and at least one FCT chemical.

The invention also includes treatment systems and methods for reducingthe occurrence of at least one problem chosen from ash accumulation andcorrosion. One embodiment includes at least one apparatus configured totransfer air through one or more combustion system ports. In oneembodiment, an air mover, e.g. a blower or compressor, is connected tothe apparatus and is configured to generate an air velocity chosen fromabout 50 to about 300 m/s, and a volumetric flow chosen from about 50 toabout 4000 ACFM. In another embodiment, an apparatus is in communicationwith a chemical storage system, e.g. the apparatus is in communicationwith a passage for feeding at least one FCT chemical to the apparatus.In another embodiment, an apparatus is in communication with a liquidsupply.

The invention also includes combustion systems having improvedefficiency. One embodiment includes a combustion system having atreatment system for reducing the occurrence of at least one problemchosen from ash accumulation and corrosion.

The invention also includes kits for reducing the occurrence of at leastone problem chosen from ash accumulation and corrosion. One embodimentincludes an apparatus having an air mover-interface and an air moverhaving an apparatus-interface. The apparatus and the air mover areconfigured to functionally connect through their interfaces. The airmover is configured to generate an air flow velocity of about 50 toabout 300 m/s, and a volumetric flow of about 50 to about 4000 ACFM. Inanother embodiment, the kit includes a port-mount configured to attachto the apparatus and mount to a port of a combustion system. In anotherembodiment, the kit includes a chemical delivery system configured tofeed at least one FCT chemical to the apparatus.

In some embodiments, methods, systems and kits can also be used tocatalyze combustion.

The above summary was intended to summarize certain embodiments of theinvention. Methods, systems, and kits of the invention will be set forthin more detail, along with examples, in the figures and detaileddescription below. It will be apparent, however, that the detaileddescription is not intended to limit the present invention, the scope ofwhich should be properly determined by the appended claims.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 illustrates a combustion system known in the art.

FIG. 2 illustrates a combustion system according to an embodiment of theinvention.

FIG. 3 illustrates one embodiment of a treatment system of theinvention.

FIG. 4 illustrates another embodiment of a treatment system of theinvention.

FIG. 5 illustrates one embodiment of a kit of the invention.

FIG. 6 illustrates another embodiment of a treatment system.

FIG. 7 is a schematic of another embodiment of a combustion system ofthe invention.

FIG. 8 is a schematic of one embodiment of a chemical delivery system ofthe invention.

DETAILED DESCRIPTION OF CERTAIN EMBODIMENTS

This disclosure is directed to methods, systems, and kits for reducingthe occurrence of problems on an internal surface of a combustion system(ISCS). Additionally, embodiments of the invention are directed tocombustion systems operated with improved efficiency. The currentdisclosure is readily understood by one of ordinary skill in the art inlight of the definitions and detailed description below.

DEFINITIONS

As Used Herein:

A combustion system is any system having a chamber and an apparatus,e.g. a burner, for burning/producing an exothermic reaction of afuel/combustion medium, e.g. a solid or liquid, located in the chamber.

A combustion system's radiant zone is any area in a combustion systemthat is visibly in line with a flame produced by at least one burner. Itshould be noted that if an object is positioned within the radiant zone,all surfaces of the object within the radiant zone are considered to bein the radiant zone. For example, surfaces of the object that face theflame, as well as surfaces of the object opposite from the flame, areconsidered to be in the radiant zone. FIG. 2 illustrates one example ofa radiant zone, zone 28 a, showing a plurality of surfaces containedwithin zone 28 a.

A downstream radiant zone is the portion of the radiant zone from thedownstream-most burner to the downstream-most portion of the radiantzone. FIG. 2 illustrates one example of a downstream radiant zone, zone28 d, showing a plurality of surfaces contained within zone 28 d.

An upstream radiant zone is the portion of the radiant zone from theupstream-most burner to the upstream-most portion of the radiant zone.FIG. 2 illustrates one example of an upstream radiant zone, zone 28 b,showing a plurality of surfaces contained within zone 28 b.

A burner zone is the portion of the radiant zone adjacent to the burneror from the downstream-most burner to the upstream-most burner. FIG. 2illustrates one example of a burner zone, zone 28 c, showing a pluralityof surfaces contained within zone 28 c.

A combustion system's convection zone is the area of the combustionsystem from the downstream-most portion of the radiant zone to thecombustion system exit. FIG. 2 illustrates one example of a convectionzone, zone 28 e, showing a plurality of surfaces contained within zone28 e.

An internal surface of a combustion system or ISCS includes any surfaceof a combustion system located in the radiant zone or the conventionzone of a combustion system.

A fireside chemical treatment chemical or FCT chemical is a chemicalcapable of at least one of reducing ash accumulation, reducingcorrosion, or catalyzing combustion. Exemplary FCT chemicals forreducing ash accumulation include Mg, Ca, Cu, Al, K, and Mn, and theirsalts, as the active groups, e.g., MgO, Mg(OH)₂, MgCl₂, TiO₂, Al₂O₃,CuCl₂.3Cu(OH)₂ (Copper Oxychloride), MnCl₂, Ca(NO₃)₂, NH₄NO₃. FCTchemicals are also inclusive of FCT chemicals as described above inhydrated form, e.g., Al₂O₃(H₂O)_(x). Exemplary FCT chemicals forreducing corrosion or further reducing corrosion beyond the use of FCTchemicals capable of reducing ash accumulation include sulfur-basedcompounds capable of releasing SO₂ or SO₃, e.g., a sulfate salt, abisulfate salt, sulfur, sulfuric acid, or ammonium sulfate ((NH₄)₂SO₄).FCT chemicals capable of catalyzing combustion include chemicals capableof reducing the amount of unburned carbon in fuel/combustion mediumburnt in the combustion chamber, e.g., by lowering the ignitiontemperature. Exemplary FCT chemicals for catalyzing combustion includecopper, manganese, and calcium nitrate. FCT chemicals are also inclusiveof FCT chemicals as described above in combination with other elements,for example, silica in combination with MgO or CaO may be used.

Ash accumulation includes any accumulation of ash or other fuelcomponents that occurs on surfaces in the radiant zone or convectionzone. Ash accumulation is intended to be inclusive of fouling, slag,clinker, and the various other terminologies used in the art to refer tothe accumulation of ash and other fuel components. Fouling, for example,can refer to the accumulation of ash or other fuel components in theconvection zone. Slag, for example, can refer to the accumulation of ashor other fuel components in the radiant zone. Clinkers can refer theaccumulation of slag in an amount large enough to dislodge from asurface under its own weight. A variety of other terminologies may beused, sometimes interchangeably, depending on the location or type ofcombustion system, and it should be clear that ash accumulationencompasses all such terminologies unless otherwise indicated. Examplesof ash accumulation include the accumulation of sodium and potassiumsalts of sulfates.

In addition to being inclusive of ash and fuel components that adheredirectly to surfaces, ash accumulation is also inclusive of ash and fuelcomponents that adhere indirectly to surfaces or that adhere bothdirectly and indirectly, e.g., ash and fuel components whose adherenceto surfaces is facilitated or further facilitated by the addition ofchemistry into the combustion system. For example, in some situationschemical compounds may be added to the combustion system to improveoperating efficiency, and the chemical compounds or their reactionproducts may accumulate on various surfaces in a manner that increasesthe accumulation of ash and fuel components. For example, when aselective catalytic reduction (SCR) system is in use, ammonia or anammonia precursor may react with SO₃ in the flue gas to form ammoniumbisulfate. Ammonium bisulfate may accumulate on surfaces in a mannerthat causes, or increases, the accumulation of ash and fuel components.Applicants believe that indirect adherence may be more problematic inareas of the convention zone, and in particular in areas of theconvection zone having temperatures less than about 800° F., and moretypically in areas having a temperature chosen from about 300 to about700° F.

Combustion problems include ash accumulation, corrosion, and incompletecombustion.

FIG. 2 illustrates one example of a combustion system 20 includingcombustion chamber 24. Fuel is injected into chamber 24 through feed 25,where it is ignited by burners 25 a, thereby producing flame 25 b andflue gas 25 c. The combustion process may cause at least one problemchosen from ash acumulation and corrosion on any number of the internalsurfaces of a combustion system (the ISCSs).

In system 20, for example, ISCSs capable of experiencing at least one ofthe above mentioned problems include internal walls 27 a, boiler drum 27b, superheater 27 c, reheater 27 d, economizer 27 e, etc. In othercombustion systems, ISCSs may be somewhat different, e.g., of adifferent size, location, or function.

In some combustion systems, it may be useful to further define physicallocation based on radiant zones and convection zones. For example,system 20 illustrates radiant zone 28 a and convection zone 28 e.Radiant zone 28 a may be further divided into upper radiant zone 28 b,burner zone 28 c, and lower radiant zone 28 d. Ash accumulation andcorrosion are illustrated at 25 c in lower radiant zone 28 d; at 25 d inburner zone 28 c; at 25 e in upper radiant zone 28 b, and at 25 f inconvection zone 28 e.

Combustion system 20 also includes at least one treatment system, e.g.,32 a, 32 b, 32 c, or 32 d, for reducing the occurrence of at least oneof ash accumulation and corrosion. Treatment systems may also be used tocatalyze combustion, for example, in areas of the combustion systemexperiencing incomplete combustion. FIG. 3 shows a close-up view of oneembodiment of a treatment system, treatment system 32 a. Treatmentsystem 32 a is positioned adjacent to the wall of combustion chamber 24,which defines port 29. Ports may vary from embodiment to embodiment. Forexample, port 29 may be a preexisting viewing port, or a port added toaccommodate treatment systems of the invention. A plurality of ports 29may be seen in FIG. 2. Referring back to FIG. 3, system 32 a includesapparatus 34 configured to provide air through port 29. Air mover 36 isconnected to apparatus 34. As used herein, air mover is intended toinclude blowers and compressors. In the embodiment shown, apparatus 34includes air mover-interface 34 a, and air mover 36 includesapparatus-interface 36 a, which allow the apparatus and air mover tofunctionally connect through their respective interfaces. In thedepicted embodiment, air mover-interface and apparatus-interface areconnected through flexible portion 38, which may be used to allowapplication apparatus 34 to achieve a sufficient range of motion forinstallation and operation. Flexible portions may be connected to eitherinterface or may be distinct pieces. Other embodiments include otherinterface structures.

In many embodiments, the air mover is mounted directly to the apparatus,meaning it is positioned from at least one of within 5 feet of theapparatus, within 4 feet of the apparatus, within 3 feet of theapparatus, or within 2 feet of the apparatus. Such embodiments may beused to provide compact, independent systems that are readily movableand adjustable to target a variety of problems in a variety oflocations.

Air movers may vary from embodiment to embodiment. In many embodiments,air movers will be configured to generate an air flow velocity of about50 m/s to about 300 m/s. In some embodiments, air movers will beconfigured to generate an air flow velocity of about 100 m/s to about150 m/s. In some embodiments, air movers are configured to generate avolumetric flow of about 50 to about 4000 actual cubic feet per minute(ACFM). Volumetric flow is often chosen from at least one of about 100to about 3500 ACFM, about 150 to about 3500 ACFM, about 200 to about3000 ACFM, about 250 to about 2500 ACFM, about 300 to about 2500 ACFM,about 350 to about 2500 ACFM, about 400 to about 2500 ACFM, about 450 toabout 2500 ACFM, about 500 to about 2500 ACFM, about 550 to about 2500ACFM, about 600 to about 2500 ACFM, about 650 to about 2500 ACFM, about700 to about 2500 ACFM, about 750 to about 2500 ACFM, about 800 to about2500 ACFM, about 950 to about 2500 ACFM, and about 1000 to about 2000ACFM. In many embodiments, volumetric flow will be chosen from about1000 to about 2000 ACFM. A suitable air mover, by way of example,includes a 480 VAC, 15 horsepower blower.

In many embodiments, apparatuses will also include a nozzle, e.g. nozzle34 b, to facilitate the desired flow rate or volume or both. In oneembodiment, the nozzle will be convergent, as shown.

Apparatuses may also be configured to deliver at least one FCT chemical.For example, treatment system 32 a includes an FCT delivery passage 40,e.g. a lance, tube or pipe, which is suitable for applying at least one(FCT) chemical into application air. Passage 40 is in communication withchemical storage system 42, which may include a variety of silos ortanks of various sizes. Chemical delivery systems, e.g. system 44, maybe positioned to functionally interface storage system 42 with apparatus34. Delivery systems include blowers, mechanical feeders, e.g., screwfeeders, or pump skids, for example. In some instances, apparatuses maybe gravity fed or fed through the force of the air mover. In otherembodiments, the at least one FCT chemical may be delivered to otherparts of the combustion system in other ways.

Storage system 42 is also representative of a storage system for aliquid source, e.g., water, such that a liquid is in communication withapparatus 34. Storage system 42 is also representative of a dual storagesystem for FCT chemicals and liquids. In such embodiments, the apparatuscan inject a dual liquid/FCT stream.

As mentioned, FIG. 2 shows several treatment systems, for example,treatment systems 32 a, 32 b, 32 c, etc. FIG. 4 shows a close up view ofsystem 32 b, which is configured for air application. In thisembodiment, system 32 b includes apparatus 54 and air mover 56, both ofwhich may be similar to the embodiments previously described. System 32does not contain an FTC passage or storage system. Additionally, system32 a is shown with port-mount 60. Port-mounts may have a variety ofstructural configurations, but are typically configured to helpstabilize the apparatus for application of air. In the embodiment shown,the port-mount is attached to the wall in an area adjacent to the port,but in other embodiments, port mounts may attach at other places, e.g.,the floor. In some embodiments, the port-mount will be configured toallow the injector to inject in a plurality of directions. In theembodiment shown, for example, injector 54 pivots about axis 60 a toallow for injection in a plurality of directions.

In some instances, it may be desirable to include a control system,e.g., CPU 50, that is functionally interfaceable with one or moretreatment systems or the various components of treatment systems.Control systems may be used to control, for example, air flow,volumetric flow, chemical injection, liquid injection, or anycombination thereof. In some embodiments, systems may be remotelycontrolled or may be controlled by a switch, valve, or dial.

The current disclosure is also directed to methods. Many embodiments aredirected to methods of operating a combustion system to reduce at leastone problem chosen from ash accumulation and corrosion. Embodiments mayalso be directed to catalyzing combustion. Although methods may beexplained, at least in part, in light of the systems described above,methods are not limited by the system descriptions, which are usedsimply to facilitate an understanding of the invention.

In many embodiments, methods include providing a combustion systemcapable of emitting a flue gas and applying air to an internal surfaceof the combustion system (an ISCS) to reduce the occurrence of at leastone combustion problem, e.g., at least one of ash accumulation,corrosion and incomplete combustion. Providing a combustion system mayvary from embodiment to embodiment. In some embodiments, providingincludes constructing a combustion system. In other embodiments,providing includes locating a combustion system. In other embodiments,providing includes gaining access to a combustion system, e.g. for thepurpose of installing a treatment system. In other embodiments,providing is achieved by operating a combustion system.

The application of air to the ISCS occurs by transferring air from oneor more entry points of the combustion system to the ISCS using at leastone apparatus. Entry points include, for example, the various portsdescribed above, which can be used or created to gain access to acombustion chamber or an ISCS. Apparatuses include any structure capableof achieving the desired air transfer, e.g., any of the apparatusesshown or described herein. Some apparatuses are configured to point in avariety of directions by being adjustably positioned within a givenport, e.g., pivotally mounted. In some embodiments, a plurality of portsmay also be used to inject into the system at various locations or topoint at particular ISCSs. Further, in some embodiments it may benecessary to apply air through a port that is upstream from an ISCS ofconcern to allow the applied air to contact the ISCS.

Air velocity and volumetric flow may vary from embodiment to embodiment.For example, air may be applied with a velocity chosen from about 50 toabout 300 m/s, more typically, chosen from about 100 m/s to about 150m/s. In many embodiments, air will be applied with a volumetric flowchosen from about 50 to about 4000 ACFM. In some embodiments, volumetricflow will be chosen from at least one of about 100 to about 3500 ACFM,about 150 to about 3500 ACFM, about 200 to about 3000 ACFM, about 250 toabout 2500 ACFM, about 300 to about 2500 ACFM, about 350 to about 2500ACFM, about 400 to about 2500 ACFM, about 450 to about 2500 ACFM, about500 to about 2500 ACFM, about 550 to about 2500 ACFM, about 600 to about2500 ACFM, about 650 to about 2500 ACFM, about 700 to about 2500 ACFM,about 750 to about 2500 ACFM, about 800 to about 2500 ACFM, about 950 toabout 2500 ACFM, and about 1000 to about 2000 ACFM.

In some embodiments, application of air will be sufficient to raise theash-fusion temperature of ash in the flue gas that contacts the ISCS.Not to be limited to any particular mechanism, applicants believe thatash-fusion temperature may be increased by, inter alia, increasing theoxygen concentration of the flue gas contacting the ISCS or bydecreasing the CO concentration, or by a combination of both. Forexample, applicants believe that when the flue gas oxygen concentrationis about 0.5% or lower, the ash-fusion temperature is lower and thepropensity of ash to accumulate and cause corrosion increases. Raisingthe ash-fusion temperature may be advantageous in both the radiant zoneand in the convection zone, but applicants believe it to be particularlyadvantageous in the radiant zone.

To determine if the ash-fusion temperature is increased, a pre-treatmentmeasurement of ash-fusion temperature can be obtained by molding asample of ash into the form of a cone having a given dimension andplacing that sample into an oven along with a temperature probe at agiven temperature. Temperature in the oven is then increased. The samplecan then be viewed through an observation window to record thedeformation temperature (temperature where the tip of the cone firstbecome rounded). A treatment measurement is then obtained by followingthe same procedure, while exposing the treatment sample to a treatmentas described herein.

In some embodiments, applied air is sufficient to increase the oxygenconcentration in flue gas contacting the ISCS portions of concern toabout 2% or greater, typically greater, e.g., 2.5%, 3%, 3.5%, 4%, 4.5%,etc. In some embodiments, air is applied by pulling ambient air using ablower or other device positioned outside of the combustion chamber. Asa result, oxygen concentrations of the injected air may range from about10% to about 30%, more commonly about 20%. In some embodiments, theoxygen concentration may be increased, for example, with O₂ or O₂enriched air.

In some embodiments, the applied air is sufficient to decrease the COconcentration in flue gas contacting the ISCS from above 5000 ppm CO toless than 5000 ppm CO. As a result, localized areas of lower COconcentration adjacent to the ISCS may be created. In some instances, COconcentration may be lowered to at least one of below about 4000 ppm,below about 3000 ppm, below about 2000 ppm, or below about 1000 ppm CO.In other embodiments, CO concentration may be lowered to at least one ofbelow about 500 ppm, below about 400 ppm, below about 300 ppm, belowabout 200 ppm, or below about 100 ppm.

In some embodiments, the oxygen concentration of the applied air will besufficient to raise the oxygen concentration of the flue gas contactingthe ISCS, e.g., to about 2% or greater, and will be sufficient to lowerthe CO concentration of the flue gas contacting the ISCS to at least oneof less than about 5000, less than about 4000, less than about 3000,less than about 2000, or less than about 1000 ppm.

The determination of CO and oxygen levels may be performed using any ofthe various measurement probes known in the art, for example, a watercooled extraction probe, such as an HVT probe available from GraceConsulting, Inc. For making the measurements referenced herein the probemay be placed within three feet of the ISCS of concern. As used herein,flue gas traveling within three feet of a ISCS is considered to contactthe ISCS or considered to contain ash capable of contacting the ISCS. Insome situations, probe positioning may be difficult to achieve due to,for example, port location or combustion system configuration. In suchsituations, measurements may be taken from the closest available portand CO and oxygen levels at the ISCS of concern may be estimated usingcomputational fluid dynamics (CFD) modeling software, e.g., FLUENTsoftware available from Fluent, Inc. of Lebanon, N.H.

Some embodiments also include applying an effective amount of at leastone fireside chemical treatment (FCT) chemical into the combustionsystem. FCT chemicals may be applied in a variety of ways. In someembodiments, FCT chemicals will be fed into the applied air, e.g., usingapparatuses, feeders and passages previously described, such that FCTchemicals and air are applied simultaneously. Feeding an FCT chemicalinto the applied air may be useful for, inter alia, allowing the FCTchemical to be delivered to a localized area of lower CO concentrationcreated by the applied air. In other embodiments, FCT chemicals may beapplied in other ways, e.g., using other devices in other locations,such as, upstream or downstream from the applied air.

As used herein, an effective amount of at least one FCT chemical is anyamount sufficient to reduce at least one of ash accumulation andcorrosion relative to applied air alone, or any amount sufficient tocatalyze combustion in a manner that reduces the quantity of unburnedfuel relative to applied air alone. FCT chemicals may be applied at avariety of rates depending on the combustion system parameters. Suitablerates may include, for example, at least one rate chosen from 5 to 100pph. Suitable rates may also include higher rates, e.g., at least onerate chose from 100 to 200 pph or 200 to 300 pph may be used. Still,higher rates may be required in some situations, e.g., large boilers mayrequire higher rates exceeding 300 pph or exceeding 400 pph.

As illustrated in FIG. 2, ISCSs of concern may be located in a varietyof locations, e.g., in an upstream radiant zone, in a burner zone, in adownstream radiant zone, in a convection zone, or any combinationthereof. As such, methods include positioning the at least oneapplication apparatus in a variety of locations. Suitable locationsinclude positioning the apparatus to apply through at least one portpositioned in the wall of the combustion system. Walls may be a wallsurrounding an upstream radiant zone, a wall surrounding a burner zone,a wall surrounding a downstream radiant zone, or a wall surrounding aconvection zone. In many embodiments, positioning may be in anycombination of the above mentioned walls. Commonly, ISCSs of concernwill be in an area having a sub-stoichiometric air-fuel ratio (AFR),e.g., where there is less oxygen than is required for full combustion.In some systems, areas having a sub-stoichiometric AFR are more likelyto accumulate ash or corrode, and may be readily effected by systems andmethods according to the instant disclosure.

Some embodiments of the invention also include applying over-fired air(OFA) into the combustion system. OFA includes applying an amount of airsufficient to bring an air-fuel ratio (AFR) in a combustion system to atleast stoichiometric. Oftentimes OFA is applied at about 1 to about 40%excess combustion air. Excess combustion air is the percentage of air inexcess of the theoretical amount of air required for a stoichiometricmixture based on the amount of fuel being fed into the combustionsystem. It should be clear from the description contained herein thatapplying air into a combustion system through at least one applicationapparatus to treat an ISCS is not applying OFA.

In embodiments where OFA is applied, applying air into the systemthrough at least one application apparatus to treat an ISCS may include,for example, applying in the radiant zone at a location upstream fromwhere the OFA is applied and downstream from where the OFA is applied.

Methods may also include applying at least one reducing agent into thecombustion system in an amount sufficient to lower NOx emissions.Suitable reducing agents include, for example, at least one of urea,methylol urea, methylol urea-urea condensation product, dimethylol urea,methyl urea, dimethyl urea, urea analogs, urea hydrolysis products, ureapills, ammonia, ammonia salts, ammonium carbamate, ammonium carbonate,ammonium bicarbonate, ammonium formate, ammonium oxalate,hexamethylenetetramine, ammonium salts of organic acids, 5-memberedheterocyclic hydrocarbons having at least one cyclic nitrogen,6-membered heterocyclic hydrocarbons having at least one cyclicnitrogen, hydroxy amino hydrocarbons, cyanuric acid, amino acids,proteins, monoethanolamine, guanidine, guanidine carbonate, biguanidine,guanylurea sulfate, melamine, dicyandiamide, calcium cyanamide, biuret,or 1,1′-azobisformamide. Reducing agents may be applied throughapparatuses described above, for example, in combination with appliedair, or by other methods, e.g., injectors positioned to inject into theradiant zone or the convection zone.

Some embodiments also including identifying an ISCS exhibiting at leastone of the aforementioned problems and pointing at least one applicationdevice in the direction of the identified portion of the ISCS. ISCSidentification may vary from combustion system to combustion system andwithin individual combustion systems. The identification of ISCSs ofconcern may be performed in a variety of ways, for example, by visualinspection, e.g., by spotting ash accumulation or corrosion; bydecreased boiler efficiency; or by historical knowledge of systemperformance. Identification may also be facilitated by the use of aprobe to determine surfaces or locations where oxygen concentration maybe below a certain threshold (e.g., less than about 1% or less thanabout 0.5%), or where CO concentration may be greater than a certainthreshold (e.g., greater than about 2000 ppm, about 3000 ppm, about 4000ppm, about 5000 ppm, or about 6000 ppm).

In many embodiments, methods of the invention will also includeinjecting a liquid with the injected air, thereby creating a dualliquid/air stream. Typically, the liquid will be water. In otherembodiments, injecting may include air, liquid, and at least one FCTchemical, e.g., creating a slurry or suspension of FCT chemical, whichmay further facilitate applying air and at least one FCT chemical to anISCS of concern.

FIG. 2 may be used to illustrate some method embodiments according tothe invention. For example, in one embodiment, visual inspection throughport 29 reveals the accumulation of ash 25 c ¹ on a surface ofsuperheater 27 c. System 32 a, including apparatus 34 (e.g., shown inFIG. 3), is positioned to transfer air from outside of the combustionchamber to superheater 27 c. Air x is applied through system 32 a at 150m/s and 1500 ACFM downstream from OFA in a manner sufficient toeffectuate a reduction in ash accumulation 25 c ¹. Reduction iseffectuated, at least in part, by raising the ash-fusion temperature ofash contained in flue gas 25 c, which contacts superheater 27 c. Thismethod further decreases corrosion of superheater 27 c.

In another embodiment, decreased heat transfer and historical knowledgeof system performance indicates the accumulation of ash 25 c ² onanother surface of superheater 27 c. Air y is applied through system 32a at 200 m/s and 2500 ACFM, thereby creating a localized area of lowerCO concentration z in flue gas contacting the superheater. Mg(OH)₂ isco-administered at 30 pph with the applied air y such that it travelsinto area z and reduces the accumulation of ash 25 c ². Otherembodiments are readily understandable in light of the disclosurecontained herein. For example, system 32 may be positioned to treat ashaccumulation or corrosion 25 f on reheater 27 d in convection zone 28 e.Treatment may be achieved by the application of air or by theapplication of air in combination with an FCT chemical. Additionally,system 32 c may be used to apply air and an FCT chemical for catalyzingcombustion into an area of the combustion chamber experiencingincomplete combustion, e.g., adjacent to walls.

The current invention also includes kits for applying air and optionallychemical to an ISCS to reduce the occurrence of at least one problemchosen from ash accumulation and corrosion. Kits may also be used forcatalyzing combustion. FIG. 5 illustrates components and optionalcomponents of one embodiment of a kit 70. Kit 70 includes apparatus 72configured to connect with air mover 74. Connection may be achieved byconnecting air mover-interface 72 b to apparatus-interface 74 a throughflexible portion 79. Air movers and apparatuses used in the various kitembodiments may be any of those of the treatment systems describedabove.

Kits will also commonly include a port-mount, e.g. port-mount 80,configured to stabilize apparatuses for application through a port,sometime in a plurality of directions.

Kit 70 may also include any or all of FCT passage 82, chemical deliverysystem 84 (depicted as a screw feed having housing 84 a and screw 84 b),or chemical storage system 86. These components are all configured toassemble, e.g., to make treatment systems similar to those describedabove.

Kits may also include a control system (e.g., system 50 of FIG. 2) thatis functionally interfaceable with the treatment system. In manyembodiments, it may be desirable to control, for example, air flow,volumetric flow, chemical injection, liquid injection, or anycombination thereof, for example.

FIG. 6 shows a partial view of another embodiment of a treatment system90. System 90 includes apparatus 92 configured to inject through one ofthe ports previously described. An air mover (not shown in this figure)connects to apparatus 92 through air mover-interface 92 a throughflexible portion 94, such as, 3 inch hose having a high temperatureresistance. The air mover in this embodiment may be any of thosepreviously described.

Treatment system 90 also includes FCT delivery passage 96 feeding to theapparatus. In this embodiment, a plurality of feed tubes, 100 a, 100 b,and 100 c feed to passage 96. The feed tubes could be used to feed avariety of different FCT chemicals or liquids. For example, tube 100 acould be in communication with any of the FCT chemicals described above;tube 100 b could be in communication with another of the FCT chemicalsdescribed above; and tube 100 c could be in communication with a liquidsource, e.g., water, thereby potentially creating a dual chemical/liquidstream for injection. Valves 102 a, 102 b, and 102 c can be used tooptionally control flow of any ingredient. System 90 is also readilyadapted to create kits of the instant invention, as described above.

FIG. 7 shows a schematic of one embodiment of combustion systemaccording to the invention. Combustion system 110 shows apparatuses 112a and 112 b positioned to transfer air into combustion chamber 114.Apparatuses 112 a and 112 b are in communication with water regulator116, compressed air regulator 118, and chemical pump skid 120 throughpassage assemblies 122 a, 122 b, 122 c. Passage assemblies 122 a, 122 b,122 c include gate valves G and 20 psi check valves C. Portions 115illustrate the combination passage-apparatus assembly.

Apparatuses 112 a and 112 b are also in communication with 480 VAC, 15HP blower motor 124, having air inlet 124 a and air outlet 124 b. Bloweris flexibly connected to manifold 126 through 6 inch low temperatureblower hose 128. Manifold 126 is flexibly connected to apparatuses 112 aand 112 b through 3 inch low temperature blower hose 130 a and 3 inchhigh temperature blower hose 130 b. Waste gate 132 is also connected tomanifold 126.

FIG. 8 shows a schematic of one embodiment of a chemical delivery systemof the invention. Delivery system 140 is configured to deliver chemicalsfrom chemical storage 142 to passage assemblies 144 via lines 146 and148. Passage 144 may be any of the passages previously described asfeeding FCT chemicals to apparatuses of the invention. Variable torquepump 150 is used to vary chemical feed based on load input 152, e.g.,analog 4-20 mA load following. Input 154 is used to remotely start andstop pump 150. A pressure reducing valve 156 set at 300 psi and a 50 psicheck valve 158 are used to additionally regulate pressure. A 1,000 mlcalibration column 160 is used to calibrate chemical injection asneeded. Bucket strainer 162 is used to strain chemicals prior toinjection. Gate valves G and drains D are also used to facilitate flowcontrol. Lines L are 1 inch stainless steel header assemblies. Theschematics of FIGS. 7 and 8 may also be useful for performing additionalembodiments of the invention, e.g., other method or system embodiments.

Systems, kits and methods of the present invention are believed toimpart a number of advantages in the art. In particular, they arebelieved to improve the efficiency of combustion systems, for example,by increasing heat exchange efficiency by reducing at least one of ashformation and corrosion. Embodiments may also be used to catalyzecombustion. In addition, some embodiments can reduce the number oftreatment location sites needed to treat the various problems mentioned.Systems, kits and methods can also be used to reduce FCT chemical use.Systems, kits and methods may also provide additional advantages. Forexample, they are readily portable and allow for rapid testing and easyadjustment for tuning to create the desired air flow and optionalchemical injection. Kits of the invention are useful because, interalia, they allow for easy transport and storage of systems as describedherein.

Although ash accumulation, corrosion, and combustion efficiency may varyfrom combustion system to combustion system, embodiments of theinvention can readily be practiced by one of ordinary skill in the artusing the teachings contained herein. By way of example, one could: (1)determine the location of problematic ash accumulation or corrosion onan ISCS; (2) assess the location of available ports or locations forcreating ports on the combustion system that could receive the air flowand likely have a positive impact (e.g., make more oxidizing) on theatmosphere around the ash accumulation or corrosion when the air istransferred through the port at a specific volumetric flow rate andvelocity, e.g., any of the flow rates or velocities described above; (3)perform a computational fluid dynamics (CFD) model of the combustionsystem to confirm that this has the desired effect on the atmospherearound the ash accumulation, e.g., using FLUENT software available fromFluent, Inc. of Lebanon, N.H.; (4) repeats steps 1-3 as necessary todetermine the optimum design requirements; and (5) specify the requiredair movers(s), air conveying duct system(s), and application device(s)to achieve the requirements of the design. A similar design can becoupled with the optional application of at least one FCT chemical asnecessary. A similar design can also be used to practice embodiments forcatalyzing combustion.

The table below illustrates exemplary combustion system operatingconditions. Example 1 is a baseline case utilizing traditional slagreduction control technology. Example 2 is similar to the baseline casewith the addition of an over-fired air (OFA) system for reducing NO_(x)emissions. Example 3 is a hypothetical illustration according to oneembodiment of the invention. Example 4 is another hypotheticalillustration according to one embodiment of the invention.

Ex. 2 Ex. 3 Ex. 4 Ex. 1 Over-Fired Ex. Ex. Unit Baseline Air EmbodimentEmbodiment System load MW 122 122 122 122 gross Net load MW net 109 109109 109 System firing rate MMBtu/ 1226 1226 1226 1226 hr System excessO2 %-wet 2.6 2.6 2.6 2.6 System excess Air % 14.9 14.9 14.9 14.9 Systemcoal flow kpph 187 187 187 187 Primary air flow rate through kpph 607476 476 476 bed grid Primary air flow rate through kpph 313 182 182 18214 ports Primary air temperature Deg F. 434 434 434 434 Secondary airflow rate kpph 0 262 262 262 through 18 injection devices for over-firedair NOX emissions reduction Secondary air through 4 start- kpph 104 104104 104 up burners Secondary air through 4 coal kpph 65 65 65 65 feedersEMBODIMENT INJECTION ACFM NA NA 1200 1200 VOLUMETRIC FLOW through 4injectors (cumulative) EMBODIMENT INJECTION m/s NA NA 100 100 VELOCITYthrough 4 injectors (average) EMBODIMENT INJECTION F. NA NA 2100 2100ZONE TEMPERATURE Air flow rate through FCT kpph 11.5 11.5 11.5 11.5Chemical injection Secondary air temperature Deg F. 401 401 401 401 FCTChemical injection rate pph 40 40 30 35

Numerous characteristics and advantages have been set forth in theforegoing description, together with details of structure and function.The disclosure, however, is illustrative only and changes may be made indetail, especially in matters of shape, size, and arrangement of parts,within the principle of the invention, to the full extent indicated bythe broad general meaning of the terms in which the general claims areexpressed.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the invention are approximations, the numericalvalues set forth in the specific examples are reported as precisely aspossible. Any numerical value, however, inherently contains certainerrors necessarily resulting from the standard deviation found in theirrespective testing measurements. Moreover, all ranges disclosed hereinare to be understood to encompass any and all subranges subsumedtherein, and every number between the end points. For example, a statedrange of “1 to 10” should be considered to include any and all subrangesbetween (and inclusive of) the minimum value of 1 and the maximum valueof 10; that is, all subranges beginning with a minimum value of 1 ormore, e.g. 1 to 6.1, and ending with a maximum value of 10 or less,e.g., 5.5 to 10, as well as all ranges beginning and ending within theend points, e.g. 2 to 9, 3 to 8, 3 to 9, 4 to 7, and finally to eachnumber 1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 contained within the range.Additionally, any reference referred to as being “incorporated herein”is to be understood as being incorporated in its entirety.

It is further noted that, as used in this specification, the singularforms “a,” “an,” and “the” include plural referents unless expressly andunequivocally limited to one referent. Nor or any embodiments intendedto be mutually exclusive, unless expressly and unequivocally indicatedas so.

1. A method of operating a combustion system, said method comprising:providing a combustion system that emits a flue gas; and applying air toan internal surface of said combustion system (ISCS), wherein saidapplication of air to said ISCS occurs by transferring air from one ormore entry points of said combustion system to said ISCS through atleast one apparatus, which is capable of transferring air from one pointin the combustion system to another point in the combustion system,wherein said application of air to said ISCS comprises applying air at avelocity chosen from about 50 m/s to about 300 m/s, and a volumetricflow chosen from about 50 ACFM to about 4000 ACFM, and wherein saidamount of said air effectuates a reduction of at least one combustionproblem.
 2. The method of claim 1, wherein said applied air oxidizes COin said flue gas contacting said ISCS, thereby creating a localized areaof lower CO concentration.
 3. The method of claim 2, wherein saidlocalized area of lower CO concentration has a concentration chosen fromat least one of less than about 5000 ppm, less than about 4000 ppm, lessthan about 3000 ppm, less than about 2000 ppm, less than about 1000 ppmCO, less than about 500 ppm, less than about 400 ppm, less than about300 ppm, less than about 200 ppm, and less than about 100 ppm.
 4. Themethod of claim 1, wherein said applied air raises the oxygenconcentration of said flue gas contacting said ISCS to about 2% orgreater.
 5. The method of claim 1, wherein said applied air has anoxygen concentration sufficient to raise the oxygen concentration ofsaid flue gas contacting said ISCS to about 2% or greater, and lower theCO concentration of said flue gas contacting said ISCS to less thanabout 1000 ppm.
 6. The method of claim 1, wherein said applied airraises an ash-fusion temperature of ash in said flue gas contacting saidISCS.
 7. The method of claim 1, further including applying an effectiveamount of at least one fireside chemical treatment (FCT) chemical intosaid combustion system.
 8. The method of claim 7, wherein said at leastone FCT chemical is chosen from one or more of chemicals capable of atleast one of the following of reducing ash accumulation, reducingcorrosion, and catalyzing combustion.
 9. The method of claim 7, whereinsaid application of said at least one FCT chemical includes feeding saidFCT chemical into said applied air.
 10. The method of claim 9, whereinsaid application of air creates a localized area of lower COconcentration within said flue gas contacting said ISCS, and whereinsaid at least one FCT chemical is delivered to said localized area oflower CO concentration.
 11. The method of claim 1, wherein said ISCS isin an area chosen from an upstream radiant zone, a burner zone, adownstream radiant zone, and a convection zone.
 12. The method of claim1, wherein said ISCS is in an area having a sub-stoichiometric air-fuelratio (AFR).
 13. The method of claim 12, wherein said sub-stoichiometricarea is in an area chosen from at least one of an upstream radiant zone,a burner zone, a downstream radiant zone, and a convection zone.
 14. Themethod of claim 1, wherein said at least one application apparatus ispositioned to apply through at least one wall chosen from a wall in anupstream radiant zone, a wall in a burner zone, a wall in a downstreamradiant zone, and a wall in a convection zone.
 15. The method of claim1, wherein said velocity is chosen from about 50 m/s to about 150 m/s.16. The method of claim 1, wherein said volumetric flow is chosen fromat least one of about 100 to about 3500 ACFM, about 150 to about 3500ACFM, about 200 to about 3000 ACFM about 250 to about 2500 ACFM, about300 to about 2500 ACFM, about 350 to about 2500 ACFM, about 400 to about2500 ACFM, about 450 to about 2500 ACFM, about 500 to about 2500 ACFM,about 550 to about 2500 ACFM, about 600 to about 2500 ACFM, about 650 toabout 2500 ACFM, about 700 to about 2500 ACFM, about 750 to about 2500ACFM, about 800 to about 2500 ACFM, about 950 to about 2500 ACFM, andabout 1000 to about 2000 ACFM.
 17. The method of claim 1, wherein saidvolumetric flow is chosen from about 1000 to about 2000 ACFM.
 18. Themethod of claim 1, further including applying at least one reducingagent into the combustion system in an amount sufficient to lower NOxemissions; optionally, wherein said reducing agent is sprayed into anover-fired air (OFA) stream in said combustion system.
 19. The method ofclaim 18, wherein said at least one reducing agent is chosen from atleast one of urea, methylol urea, methylol urea-urea condensationproduct, dimethylol urea, urea pills, methyl urea, dimethyl urea, ureaanalogs, urea hydrolysis products, ammonia, ammonia salts, ammoniumcarbamate, ammonium carbonate, ammonium bicarbonate, ammonium formate,ammonium oxalate, hexamethylenetetramine, ammonium salts of organicacids, 5-membered heterocyclic hydrocarbons having at least one cyclicnitrogen, 6-membered heterocyclic hydrocarbons having at least onecyclic nitrogen, hydroxy amino hydrocarbons, cyanuric acid, amino acids,proteins, monoethanolamine, guanidine, guanidine carbonate, biguanidine,guanylurea sulfate, melamine, dicyandiamide, calcium cyanamide, biuret,and 1,1′-azobisformamide.
 20. The method of claim 1, further includingapplying OFA into the combustion system, wherein said OFA includes anamount of air sufficient to bring an air-fuel ratio (AFR) in saidcombustion system to at least stoichiometric.
 21. The method of claim20, wherein said OFA is applied at about 1 to about 40% excesscombustion air.
 22. The method of claim 20, wherein said applying airinto said system through at least one application apparatus to targetsaid ISCS includes applying in the radiant zone at a location upstreamfrom where said OFA is applied.
 23. The method of claim 20, wherein saidapplying air into said system through at least one application apparatusto target said ISCS includes applying in the radiant zone at a locationdownstream from where said OFA is applied.
 24. The method of claim 1,wherein said step of applying air into said system through at least oneapplication apparatus to target said ISCS is not OFA.
 25. The method ofclaim 1, further including identifying a portion of said ISCS exhibitingat least one of said problems and pointing said at least one applicationapparatus in the direction of said identified portion of said ISCS. 26.The method of claim 1, further including injecting a liquid through saidat least one application apparatus.
 27. The method of claim 1, whereinsaid combustion problem is chosen from at least one of ash accumulation,corrosion and incomplete combustion.
 28. A combustion system that emitsa flue gas, said combustion system comprising: an internal surface(ISCS) located in at least one of a radiant zone and a convection zone;an entry point for establishing communication with said ISCS; at leastone treatment system comprising an apparatus configured to transfer airfrom one point in the combustion system to another point in thecombustion system, and an air mover connected to said apparatus, whereinsaid air mover is in communication with an air supply and is configuredto generate an air flow velocity of about 50 m/s to about 300 m/s, and avolumetric flow of about 50 ACFM to about 4000 ACFM, wherein saidapparatus is positioned such that application of air through saidapparatus increases an oxygen concentration in said flue gas contactingsaid ISCS and reduces the occurrence of at least one combustion problemchosen from ash accumulation, corrosion, and incomplete combustion. 29.The combustion system of claim 28, further including an FCT deliverypassage configured to interface with said apparatus and apply an FCTchemical into said applied air, and an FCT chemical supply incommunication with said FCT delivery passage.
 30. A treatment system foruse with a combustion system that emits a flue gas, said combustionsystem having an internal surface (ISCS) located in at least one of aradiant zone and a convection zone, and an entry point for establishingcommunication with said ISCS, said treatment system comprising: anapparatus configured to transfer air from one point in the combustionsystem to another point in the combustion system, and an air moverconnected to said apparatus, wherein said air mover is in communicationwith an air supply and is configured to generate an air flow velocity ofabout 50 m/s to about 300 m/s, and a volumetric flow of about 50 ACFM toabout 4000 ACFM, whereby application of air through said apparatusincreases an oxygen concentration in flue gas contacting said ISCS. 31.The treatment system of claim 30, further including an FCT deliverypassage configured to interface with said apparatus and apply an FCTchemical into said applied air, and an FCT chemical supply incommunication with said FCT delivery passage.